I know this was a few pages back, but I was away for a bit.
Besides the neglible increase in armour rating how is a dude with 117 light better than a dude with 110 light. The armour rating increase doesn't even do that much. They both probably die in the same amount of shots. Light is one of the oddest systems in terms of leveling I've ever encountered. Lvl 29 is lvl 29, it's honestly one of the silliest systems ever. Not to mention that I'm incredibly bothered by how it obsoletes gear and railroads everyone into one specific set of gear, they've got shit for loot variety all ready and they've made it even smaller with the light requirement.
Light functions in both manners. More light both reduces damage taken and increases damage given, assuming equal level to the mob you're damaging. As I said in the post you quoted it's not a big difference, but there is indeed a difference. It's not particularly important because the difference is small but it's worth noting because it highlights the point of that post, which is that Light Level is just a very simple way to implement a Gear Score. The whole reason why they tell you the Light Level rather than just list the exact amount of Light you have is to make it easier to know at a glance whether or not your gear is at the proper range to attempt specific level content.
Would it be fair to refer to the actual character level as the soft cap and the maximum light level as the hard cap, keep the soft cap at 20, and increase the hard cap from 30 to 32 or 33.
Not really, no because it confuses the terminology. A Hard Cap is a cap that can not move in any way. You simply can't go past it no matter what you do. A Soft Cap is typically a cap in which, once you do pass it, you get diminishing returns or to put it another way, you get less performance for the investment. In Destiny, Level 20 is a Hard Cap on your player level. However Light Levels don't really fit the terminology of Soft Cap since it's only capped by available Light on gear and once they add gear with more Light on it, it will increase.
Outside of the terminology aspect of your post, you're thoughts are directly in line with what I believe they will do going forward. Level 20 will always be hard capped there but future gear will have more Light which will raise the Light Level Cap as harder and higher level content is released.